Known thermal storage air conditioners include a thermal storage air conditioner which has a thermal storage tank which stores cold thermal energy by utilizing a thermal storage effect of a thermal storage material (i.e., a thermal storage medium) as disclosed, for example, in Patent Document 1. This thermal storage air conditioner performs a utilization cooling operation for cooling, e.g., a room, by utilizing the cold thermal energy stored in the thermal storage tank, a general cooling operation for cooling the room without utilizing the cold thermal energy stored in the thermal storage tank, and a cold thermal energy storage operation for storing cold thermal energy in the thermal storage material.